Ever since I installed my Procharger D1SC on my 05 MN6 coupe, I have been experiencing a problem with the engine shutting down and the DIC reading “Reduced Engine Power” and “Service Active Handling” if it is not turned off. This seems to happen only when I begin reaching Boost levels around 2-3 psi (Maximum is 8psi). It does not do it every time, but most of the time.

Initially the first 2-3 times it happened I also got a check engine light. The codes were PO120, PO121, and/or PO122. Can’t remember which two of the three I had for sure. These were cleared by LG Motorsports Tuesday when they did the tune and also the first failure after I left their shop and returned. The check engine light has not occurred on the other 4-5 times it has failed since.
• PO120 is “Voltage is off for TP sensor 1”
• PO121 is “Predicated air flow and the predicated MAP combined are outside a calibrated range for more than 3 seconds”
• PO122 is “Throttle Position (TP) Sensor 1 circuit low voltage”
All of these are related to the throttle body.

Some other info:
1. It never happened before I installed the Procharger
2. It has happened in all four lower gears, only when going into boost.
3. The engine sounds great until it happens and pulls very hard. After failing it goes into a very rough idle mode with hardly any response from the accelerator pedal. If you floor it, it might go to 1000 -1200 rpm. Not enough really to get it off the road!! By definition in the service manual, I guess this is “Forced Idle mode”.
4. I have had one time that I ran it through the gears with no failure, taking each of the first three gears to maximum boost.
5. When LG tuned it on the dyno, it never did it. They made several runs after final tune adjustments to 6500 rpm.
6. I have driven it for about 400 miles since and if I keep it out of boost there is no problem.
7. I tried turning off the active handling since I have been getting several “Service Active Handling” messages over the last several months. (These have only occurred when turning sharply at very slow speeds, mainly parking lots or turning around) At first, I made several spurts in the lower 4 gears and everything was working fine. Then a couple hours later, I tried it again and it failed the first time I went into boost.

Any ideas anyone? I really don’t want to take it to a dealer if I don’t have to. I’m hoping someone else has had this problem and can tell me what their solution was. Could it possibly be a loose connection? I already had one connector loose on my amp

 

There is a service bulletin out for a loose connection in the steering column that will throw the Service Active Handling message in the DIC. I think it is the connection to the steering wheel position sensor. I've also heard that this can also trigger reduced engine power because the computer thinks there is a severe handling issue with the car. Good news is that is an easy fix with a nylon zip tie. See your dealer, or search this forum for more info on the fix. Good luck.

 

Thanks, I thought of that one also. I still had the problem when I turned off Active Handling. But maybe even if if it is turned off, it still monitors that as a safety precaution? Anyway, I do need to get it fixed as it has given me the error in the past when I was making sharp turns as slow speeds.

 

I have gotten both the active handling error and the TPS error. I have no idea about the traction control system but mine works great. When I was using different wheels/tire sizes at the race track it recalibrated itself and worked flawlessley in comp mode.

The TPS is another story but here is my theory. When I got the error I was on an onramp. My RPMs were very high (5000) but my throttle position was low. So what's happening is the blower is still creating boost/heat even thought the throttle isn't asking for more air. (one of the knocks on centrifugal design) Well your blow off valve isn't necessarily designed to flow enough air when this is happening. So you are getting more airflow than the mass air and tps is expecting. Therefore it throws the error. I don't think anything is wrong since the computer isn't designed to recognized this situation. The computer was designed around 400hp NA not 600hp or whatever with a blower on it.

That's my theory, and I'm sticking to it. I have a diablosport predator to clear the errors. I have only gotten the TPS once so it doesn't bother me. I hammered on my car last weekend for two days straight road racing. I would have found the weak link if there was one.

 

I've had the issue 3 times. It's always while I'm turning and more than 50% throttle! Very Very dangerous!!! Can won't rev over 1500? RPM

 

i had tjis problem to when first installed it. the power is freaking out the computer. mine was doing it at 90 when i was spinning the tires. 400 hp wont do that so computer not used to ever seeing it. the limp mode is a bitch. just stop undo battery and it will go back to norm. you may get away with just turning car off . the car does learn and i see it less and less...actually it has been a few months since this has happened to me. also i got limp mode when my throtle position sensor wire got in my belt...may want to check that.
shane

 

When I was investigating FI I was told that there is a MAF patch that needs to be installed. Too much air flow over the MAF causes a change in voltage outside the computer calibration for a given TP and then you get the limp mode to protect itself. I would have thought that LG would be all over that so I am very reluctant to say that is it but worth a mention since tuners are human and mistakes made. Chceck MAF plug connection too. Keep us posted on whats up. After re reanding your post my expl doesnt seem applicable.

 

Sounds like the maf patch to me..

 

Actually, they did contact ATI but not sure what they found out. I will contact LG and see if they did a MAF patch.

Update: I took it out this morning and it failed on the first attempt. Did not give any codes or messages. Turned it off and it started right up. Went down the road a bit and did 3 rolling starts through the gears to about 100 without error. Maybe it is "learning". I'm tinking the MAF patch sounds like the problem, however.

 

When you went to "limp mode" did you get messages also? Did you do the tuner kit or use the furnished programmer?

 

Doug,
my first thought was the MAF patch but why wouldnt it happen on LG's dyno?

 

Dealer installed a new MAF and Throttle Body and haven't had a problem since

John

 

Did they do it under warranty? Wonder why that would fix it unless the original one was defective? It would seem the replacements would be the same capacity as the original ones? Also when they install new ones can they access the ECM after it has been tuned and locked?

 

I believe it was the throttle position sensor, that was causing the reduced engine power. And they did the Maf patch at the same time. Good luck!

 

Since I posted last, I have done 10-15 blasts in boost and it only failed one time (Well, two if you count blowing off the hose on the MAF at 8.5# boost). That was the first time when the engine was not quite warmed up. I had driven it for about 1 mile prior. After that, most pulls were to redline from a rolling start up to fourth and a few in third only when passing. Maybe I am "teaching" the computer what it is supposed to do!!

 

Well, it did it again. So far it has only done it recently when the engine is still warming up. I started it and drove about a 1/2 mile and got on it in first and down she went. I am out of town this week but will continue to troubleshoot when I return home next week.

 

I ordered Autotap software to monitor and record the parameters. Hopefully when I get home next week I can hook up my laptop and Autotap and record all the parameters to see what is happening and identify what is actually dropping off and causing the engine to go to limp mode.

I am still accepting comments and proposed solutions until then. I will let you know what I find out in a week or so.

 

 

DG,
Search my posts...I spent many, many, man hours on this one... It's a tuning issue... Starting with the maf patch and a few easy (read 2 minutes worth of work start to finish) tuning tweaks in the tuning program...PROMISE...

 

I hope you had your car custom tuned? If not, there are a few things that need to be tweaked on the tune to make sure it runs right and doesnt freak out from the extra heat and whatnot that comes from the blower.